The present invention relates to window coverings and more specifically relates to window coverings having cells adapted for selectively controlling the amount of light passing through the window covering and to methods of making such window coverings.
For many years, window coverings have been used to at least partially cover a window opening and selectively close off the view therethrough. One well-known type of window covering is a venetian blind having a large number of elongated slats. In order to improve the energy efficiency of buildings and to decrease the amount of heat escaping through window openings, cellular shades were developed that replaced the slats of a venetian blind with a plurality of air trapping cells. The air trapping cells are typically formed by shaping or folding a fabric material, such as cloth, into a plurality of elongated loops. The elongated loops are then connected together and comprise the body of the window covering. Thus, a typical cellular shade includes a horizontally arranged head rail, a horizontally arranged bottom rail remote therefrom, and a plurality of cells there between being interconnected one atop of the other.
In a top pulling shade, the lowermost cell in the window covering is received in or attached to the bottom rail and the bottom rail is interconnected with the cells and the head rail by at least one lifting cord. When the lifting cord is pulled, the bottom rail assembly attached to the cord moves in an upward direction toward the head rail, thereby causing the individual cells to collapse into substantially flat sections. During upward movement of the bottom rail, the individual cells preferably collapse in series from the lowermost cell to the uppermost cell. When the window covering is fully opened, all of the cells are collapsed to provide a final structure having a bottom rail assembly, a stack of collapsed cells thereon and a head rail assembly disposed at the top of the window opening. In order to close the cellular shade, the lift cord is manipulated so that the bottom rail falls or moves away from the head rail, thereby carrying the stack of collapsed cells downward. During downward movement of the bottom rail, the uppermost cell of the window covering will open first and the remaining cells will open in series from the uppermost cell to the lowermost cell. If the bottom rail is stopped or secured in place between the fully opened position and the closed position, the window covering will have a series of cells (adjacent the top rail) that are open and a series of cells (adjacent the bottom rail) that are collapsed or folded.
The prior art discloses various methods and apparatus for forming an expandable cellular shade for window openings. U.S. Pat. Nos. 3,963,549 and 4,603,072, disclose methods of making a cellular structure from a plurality of separate tubes or separate strips that are folded into a tubular configuration, and adhered together, one on top of the other, to form longitudinally extending cells. U.S. Pat. Nos. 4,288,485 and 4,346,132 disclose methods of making a cellular structure from a plurality of sheets that are stacked and adhered together along spaced bands to form a plurality of cells between adjacent sheets. U.S. Pat. Nos. 4,631,217 and 4,677,012 disclose a method of making a cellular structure from a plurality of separate sheets that are longitudinally folded and adhered together such that each sheet forms a part of two adjacent cells. U.S. Pat. Nos. 2,201,356 and 4,625,786 disclose forming a cellular structure from two folded sheets disposed at opposite sides of a shade and connected together at spaced locations.
Commonly assigned U.S. Pat. No. 5,160,563, the disclosure of which is hereby incorporated by reference herein, discloses a method and apparatus for making a pleated expandable and collapsible multi-cell window covering. A web of material is accordion folded widthwise to form a series of web panels united in alternate succession along first and second creased folds disposed at respective first and second sides of the web. Successive panels are advanced in an unfolded condition lengthwise of the web through an adhesive applying zone to an inlet end of a refold stack and adhesive is applied to each web panel, in a band parallel to and spaced from the associated creased fold with a preceding panel. The web panels having adhesive applied thereto are refolded in succession along the associated creased fold with a preceding panel onto the inlet end of the refold stack. The band of adhesive is applied at the second side of the web to each panel that joined along a first creased fold to a preceding web panel and the band of adhesive is applied at the first side of the web to each panel that is joined along a second creased fold to a preceding panel.
In recent years, light control cellular shades have become increasingly common, particularly those which employ one or two continuous sheets of sheer material to form the front or rear of the shade structure. For example, U.S. Pat. Nos. 5,313,999, 5,394,922 and 5,454,414 disclose light control shades in which both the front and rear sheer portions are made from a single sheet of sheer material. U.S. Pat. No. 5,664,613 discloses a light control shade which includes one continuous sheet of sheer material and a series of strips attached to the sheet having opaque and sheer portions.
Commonly assigned U.S. Pat. No. 5,702,552 to Kutchmarek et al., the disclosure of which is hereby incorporated by reference herein, discloses a method and apparatus for forming a pleated cellular shade product from a single web of material, whereby the shade has different physical characteristics on opposite sides thereof. In one embodiment, a web is provided having alternate first and second stripe areas extending across the web at predetermined intervals. The first stripes have a light transmissive character that differs from the light transmissive character of the second stripes. The web is folded in a first direction along a first fold line intermediate side edges of the first stripe area and in a second direction along a second fold line intermediate side edges of each second stripe area to form a plurality of sidewise adjacent panels, serially united in alternate succession along respective first and second fold lines. After the web has been folded, the first stripes provide the desired light transmissive characteristics on one side of the shade and the second stripes provide different light transmissive characteristics on the opposite side of the shade, without adversely affecting the appearance of the shade product. Thus, the shade product may be formed with different colors or textures at opposite sides or with a light reflection and/or absorbent surface on one side or the other for enhanced insulating characteristics.
In accordance with one preferred embodiment of the present invention, a light controlling window covering includes a plurality of elongated cells attached one atop the other. Each cell of the window covering is generally rectangular when view in cross-section and preferably includes a substantially opaque top strip at the top of the cell and a substantially opaque bottom strip at the bottom of the cell. As used herein, the term substantially opaque or opaque means that the material allows no or very little light to pass therethrough. One of the opaque strips may be colored or darkened and the other opaque strip may be white or a light color close to white. Each cell also preferably includes a front sheer strip extending vertically at a front of the window covering and a rear sheer strip extending vertically at a rear of said window covering.
In order to assemble an individual cell, an upper end of the front sheer strip is preferably folded inwardly toward a front edge of the top opaque strip and a lower end of the front sheer strip is folded inwardly toward a front edge of the bottom strip. In a similar fashion, an upper end of the rear sheer strip may be folded inwardly toward a rear edge of the top opaque strip and a lower end of the rear strip may be folded inwardly toward a rear edge of the second opaque strip. The opposed ends of the opaque top and bottom strips and the sheer strips are preferably connected together using an adhesive swirl. The adhesive swirl is preferably an elongated strand of an adhesive material that reciprocates back and forth between the opposed edges of adjacent strips. The adhesive swirl extends the length of the opposed edges and when cured forms a flexible joint between adjacent strips. The adhesive swirl preferably spans a relatively small gap between the opposed edges of the two opaque strips and the two sheer strips. After the adhesive swirl cures, the adhesive swirl provides a flexible hinge that enables the strips to be formed into a continuous loop.
In other preferred embodiments, the ends of the sheer strips overlap the ends of the opaque strips and an adhesive is disposed between the overlapped ends of the strips. Thus, in this embodiment there is no gap between opposed edges of the strips when they are arranged side-by-side.
The two sheer strips generally form the side walls of a cell and the two opaque strips generally form the top and bottom walls of the cell. In certain embodiments, the two sheer side walls may have one or more creases formed therein for enabling the cells to expand and/or collapse when the window covering is lowered to cover the window and retracted to allow a view through the window.
The front and rear sheer members are preferably made from an at least partially transparent fabric that allows substantial amounts of light to pass between the front and rear walls of each cell. The opaque strips and the sheer strips are typically made of a flexible fabric material.
After a plurality of individual cells have been formed, the cells may be stacked atop one another and connected for making a complete window shade. The cells may be connected together by depositing relatively thick beads of an adhesive material at the end portions of the front and rear sheer members. The adhesive beads are preferably placed adjacent the ends of the top wall of each cell.
The window covering preferably includes an operating element in contact with the cells of the window covering for causing relative vertical movement of the front and rear walls (i.e., sheer strips). During actuation of the operating element, relative vertical movement between the front and rear sheer strips causes the substantially opaque top and bottom strips to rotate between a first substantially horizontal position and a second non-horizontal position. In the first substantially horizontal position, the substantially opaque top and bottom strips allow substantial amounts of light to flow through the window covering, i.e., between the front and rear sheer walls. In the second non-horizontal position, the substantially opaque top and bottom strips at least partially reduce the amount of light passing through the window covering, i.e., at least partially obstruct the light flowing through the front and rear sheer walls of each cell.
The window covering also preferably includes a head rail assembly attached to an uppermost cell of the plurality of cells and a bottom rail assembly attached to a lowermost cell of the plurality of cells. The operating element also preferably includes one or more lift cords connected to the head rail and the bottom rail for raising and lowering one of the head rail and bottom rail assemblies relative to the other of the head rail and bottom rail assemblies. The top and bottom walls of each cell preferably have at least one opening through which the one or more lift cords pass. In other preferred embodiments, the one or more lift cords may pass through the adhesive swirl connecting the ends of the sheer strips and the top and bottom opaque strips.
In still further embodiments, the window covering may include a separate layer of fabric sandwiched between adjacent cells and extending toward a rear side of the window covering. Each of the rearwardly extending layers of fabric desirably includes an aperture through which the one or more lift cords may pass.
In another preferred embodiment of the present invention, a light controlling window covering includes a plurality of cells attached one atop the other. In this particular embodiment, each cell includes a substantially opaque top strip at the top of the cell, a substantially opaque bottom strip at the bottom of the cell, a substantially transparent front sheer strip extending vertically at a front of the window covering and a substantially transparent rear sheer strip extending vertically at the rear of the window covering. The front sheer strip preferably has an upper end folded inwardly toward a front edge of the top strip and a lower end folded inwardly toward a front edge of the bottom strip. The rear sheer strip preferably has an upper end folded inwardly toward a rear edge of the top strip and a lower end folded inwardly toward a rear edge of the bottom strip. The front and rear sheer strips have end portions that are flexibly connected to adjacent ends of the top and bottom opaque strips to form a generally rectangular-shaped loop. The window covering also includes an operating element in contact with the cells for causing relative vertical movement of the front and rear sheer members, wherein relative vertical movement between the front and rear sheer members causes the top and bottom strips to rotate between a first substantially horizontal position which allows light to flow between the sheer strips and a second position in which the top and bottom opaque strips at least partially obstruct the flow of light through the sheer strips.
Further preferred embodiments of the present invention provide a method of making a light control window covering having a plurality of cells including providing first and second continuous webs of substantially opaque material, providing first and second continuous webs of sheer material adapted to permit light to pass therethrough, forming an individual cell by connecting a first end of the first sheer web to a first end of the first substantially opaque web, connecting the second end of the first substantially opaque web to a first end of the second sheer web, connecting the second end of the second sheer web to a first end of the second substantially opaque web and connecting the second end of the second substantially opaque web to the second end of the first sheer web to thereby form a continuous loop of material having alternating sheer and substantially opaque portions. The forming steps include applying an adhesive between the ends of the sheer strips and the substantially opaque strips to provide a flexible hinge between the sheer strips and the substantially opaque strips.
The loop is then formed into a generally rectangular configuration and the rectangularly configured loop of material is cut into sections having a predetermined length to provide a plurality of cells. The cells are then stacked and adhered, such as by applying adhesive beads adjacent the ends of the sheer strips, to form a continuous shade. After the cells have been adhered together, the substantially opaque strips of each cell form the top and bottom walls of the cell and are positioned adjacent to opaque strips of adjacent cells. The sheer strips are preferably positioned along the side walls of each cell, i.e., along the exterior of the window covering.
The cells described above may be formed using a tube folding machine having one or more unwind stands for supplying webs of the sheer and opaque strips. The tube folding machine preferably includes a stationery support surface for supporting the strips and a pulling mechanism for pulling the strips across the support surface. The machine may also includes a trimmer for cutting the strips of sheer and opaque material after the material has been configured in a side-by-side arrangement for being adhered together. The tube forming machine may includes one or more adhesive applicators for supplying the adhesive necessary for assembly the strips together.
The tube forming machine also preferably includes a folding horn which folds the sheer strips and opaque strips into a substantially rectangular shaped tube after the strips have been adhered together. After the strips have been folded into a tube, the folding horn preferably form creases in the side walls of the tube for collapsing the side walls. The tubes are then preferably forwarded to a stacking machine. The tube stacker is preferably located downstream of the folding horn and receives the recently formed tubes discharged from the folding horn. The tube stacker receives incoming tube from roll and adheres the incoming tube to the uppermost tube of a stack of tubes that have previously been adhered together. The tube stacker includes a registration guide that guides the incoming tube into engagement with the top tube of the stack. The stack preferably remains stationary and the registration guide reciprocates back and forth between a start position and an end position. As it moves to the start position, the registration guide captures the uppermost tube in the stack and brings it into engagement with the incoming tube. The stacking element includes an adhesive applicator for applying an adhesive to the top wall of the uppermost tube as the registration guide traverses the uppermost tube.
In another preferred embodiment, the window covering is not used to control light passing through a window opening. In this embodiment, the window covering is assembled substantially similar to the steps described above, however, the cells do not include any sheer strips. As a result, the cells are substantially opaque at all times so that little or no light may pass through the shade when the shade is covering the window opening.